Direct fired water heater

ABSTRACT

A direct fired water heater comprising a rotary drum, a water inlet and a water outlet therefor, a burner generally centrally located in the drum, the burner being fixed, there being an inlet stator and an outlet stator having openings at different distances from the inner periphery of the drum providing a static pressure difference in the water.

0 United States Patent 1 1 1111 3,882,894 Iluettner 1 May 13, 1975 1DIRECT FIRED WATER HEATER 2,124,914 7/1948 Fottinger 415/89 3,384,0245/1968 King 415/89 [761 P g i 1 3,608,332 9/1971 Leonardi, Jr. 415/89nternatlona on men a 1 Corporation, 193 W. Boylston, FOREIGN PATENTS ORAPPLICATIONS Boylston, Mass- 01583 230,159 3/1963 Austria 415/89 [22]Filed: Oct. 11, 1973 1 [21] Appl. No.: 405,540 Primary Examiner-WilliamR. Cline Related U s Appmaflm Data Attorney, Agent, or Firm-Charles R.Fay

[62] Division of Ser. No. 228,290, Feb. 22, 1972, Pat. No.

3,786,798. [57] ABSTRACT [52] U S Cl 137/581, 415/89 A direct firedwater heater comprising a rotary drum, [51] F24h 1/10 a water inlet anda water outlet therefor, a burner gen- [58] Field R 350 erally centrallylocated in the drum, the burner being 60/39 2 155 137/580 Smalls/89:fixed, there being an inlet stator and an outlet stator 417/62; havingopenings at different distances from the inner periphery of the drumproviding a static pressure dif- [56] Reiemmes Cited ference 1n thewater.

UNITED STATES PATENTS 1,032,892 7/1912 Goodard et a1 415/89 4 Claims, 1Drawing Figure ROTATION DIRECT FIRED WATER HEATER This application is adivision of Ser. No. 228,290, filed Feb. 22, 1972, now US. Pat. No.3,786,798, Jan. 22, 1974.

BACKGROUND OF THE INVENTION Conventional water heaters are ordinarilycharacterized by the feature that the water to be heated and theproducts of combustion emenating from the flame are separated by a wallof some kind. The wall may be in the form of tubes or merely a containerof any shape which is heated by hot combustion products passing over oralong the same and heating the water by conduction.

Another conventional method of heating water resides in the injection ofcold water into a flame, preferably gas, thereby heating a fine spray ofwater very rapidly due to the contact with the flame. This has decideddisadvantages however; great care must be taken to inject the water at apoint where the flame is not cooled to the point of incompletecombustion; some of the finer droplets may be readily turned into steamwhich must be recondensed so as not to be lost through the chimneyeffluent, and separation of the flue gas from the water vapor requireselaborate condensing devices. Therefore, much of the inherent simplicityof such a system is negated by the necessity for elaborate ancillaryequipment.

SUMMARY OF THE INVENTION The present invention takes advantage of theextremely high heat transfer rates possible by direct contact betweenthe water and flame using a cylindrical water surface.

There is no water injected into the flame and therefore there is lesschance of vaporizing a part of the water but instead a rapidly rotatingdrum is provided with a water inlet, the water by centrifugal forceforming a cylindrical water ring or wall at the interior of the drum. Afixed fuel burner extends into the center of the drum and the flamebears at least in part upon the inner surface of said ring or wall ofwater. The diameter of the water ring is controllable while constantlyadding water and extracting it at the same time it is being heatedthrough direct contact with the flame; and this is done by providing aninlet and an outlet stator at different distances from the interiorsurface of the drum but both having openings directly into the waterring, thereby providing a differential of static pressure which iseasily measured and can be used to control the inlet and outlet of thewater.

The FIGURE in the drawing is a cross sectional view through a directfired water heater according to the present invention.

PREFERRED EMBODIMENT OF THE INVENTION A hollow cylindrical drum isprovided, this drum containing a series of circumferentially spacedinwardly directed longitudinal baffles indicated at 12, together withcircular baffles 14 having interruptions or apertures 16 therein for thepassage of water therethrough. The drum is closed at its ends by topplate 18 and by the bottom plate 20. Plate 18 is connected to a hollowshaft 22 mounted on bearings 24 internally thereof and the shaft isprovided with means such as a pulley 26 by which it is rapidly rotatedby a motor not shown.

The bearings 24 are mounted on a fixed tubular member 28 which in turnmounts an inner tubular member 30, the latter in turn mounting theburner 32 with a burner face 34 and also an ignition means 36. Outsidetube 30 there is an annular water inlet generally indicated at 38, thelatter being derived from a pipe not shown through the inlet 40. Variousseals may be utilized such as felt gasket 42 and others to preventleakage, etc.

Bottom plate 20 carries an inverted frusto-conical open ended membergenerally indicated at 44 which rotates therewith. This is provided witha series of openings only one of which is shown at 46, this having avane 48 and a rectangular outstanding rim 50 directed inwardly of theconical member 44. In stopping the burner and drum, water may collect inthe bottom of an encompassing housing 52 as in the area at 54 but onstart up, this water is sucked back up into the drum by the conicalmember 44 at least to such a degree as to constitute substantially acomplete transfer of such water into the drum.

There is a fixed inlet stator which is generally indicated at 56 and anoutlet stator generally indicated at 58. These stators each compriseessentially a pair of circular plates having a space between them exceptfor a number of curved vanes in the fashion of a closed centrifugal pumpimpeller. The diameter of the inlet stator is greater than the diameterof the projected water level which is indicated at 60, and the outletstator is constructed the same but the diameter of the outlet stator isgreater than that of the inlet stator approaching closer to the wall ofthe drum 10 and farther into the water ring.

The hot water outlet comprises a series of tubes generally indicated at62 leading into collection chamber 64 and water may be drawn off throughthe opening 66 as desired. The reference numeral 68 indicates asupporting bracket for the entire device which in general is suspendedfrom a plate 70 which can be mounted on the bracket or by any othermeans desired.

The housing 52 may be utilized as a flue passage in the area at 74between the drum and the inside wall of the housing and this exhaust forthe flue gases 76 may take any form desired but it is to be realizedthat the housing 52 is fixed and the drum 10 rotates therein in spacedrelation with respect thereto.

If a certain volume of water be admitted to the drum while it isspinning, a water ring or wall of cylindrical nature is formed having aninner surface at e.g., the indicated water level 60. The mass of thewater ring or wall is subject to a centrifugal force which causes anincreasing static pressure within the water ring or wall in a radiallyoutward direction. Therefore at a given speed of rotation the staticpressure within the water increases radially outwardly as the square ofthe radius. At the stated diameter of the inlet stator, the staticpressure within the rotating water is substantially higher than thebarometric pressure acting on the surface of the water level. Since theinlet stator is stationary, it is clear that if water is admitted to thewater inlet, and to the hollow space connecting it with the inletstator, at a static pressure equal to the static pressure surroundingthe periphery of the inlet stator, both pressures are in balance and nowater would flow ither into or out of the rotating drum. At the sametime the diameter of the water level inside the rotating drum would ofcourse not change.

The static pressure within the water ring is greater at the outletstator than at the inlet stator and water will be pumped out of theoutlet stator as long as the water outlet is open to the atmosphere. Ifnow the outlet water flow were to be shut off by means of a valve, astatic pressure is built up within the spaces between the outerperiphery of the outlet stator and that valve which would be equal tothe static pressure surrounding the periphery of the outlet stator.Again, no water would flow through the drum and the water level wouldremain at its prescribed diameter; but as the outlet valve is againopened, water is pumped out of the drum by the outlet stator whichcauses the water level to recede in a radially outward direction.Through this action, the static pressure surrounding the inlet stator atits outer periphery also decreases causing the higher static pressureand the water supply connected to the water inlet to feed water into thedrum at a rate exactly equal to that rate at which water is pumped outof the drum by the action of the outlet stator.

As long as water is being pumped through the drum in the describedmanner, the static pressure conditions around the peripheries of boththe inlet stator and the outlet stator are of course somewhat morecomplex owing to the fact that, in addition to the static pressuresmentioned, there are also certain dynamic forces involved. In otherwords, the static pressure present in the inlet, or supply, side dropssomewhat due to its conversion into dynamic head required for the flowto occur, but a similar condition also results at the point where thewater is forced into the outlet stator not only by its static pressurebut also by the dynamic energy imparted to it by the rotation of thedrum. It is for this reason that both stators are internally equippedwith curved vanes; those in the inlet stator being curved towards thedirection of rotation, and those in the outlet stator being curved inthe opposite direction against the direction of rotation so as to scoopthe water into the outlet stator, thus taking advantage of the watersvelocity head in pumping it out of the drum and into the outlet piping.By applying well known principles in fluid dynamics the designer canradily minimize flow losses and irreversible energy conversions withinthe system.

The gas burner is an integral part of the inlet stator assembly. At thetop of the unit provisions have been made for the admission of gas andair to the burner. Slots admitting air are provided with a shutter whichallows adjusting the amount of combustion air being drawn into theburner proper. The necessary draft is provided by blower vanes attachedto the conical extension of the bottom end plate whose suction effectdraws the combustion air as well as the gas through the burner intakepipe and through the burner face. This burner face is made ofalternating strips of corrugated stainless steel strip and plain stripwound around a core which also holds the ignitor electrode. Ignition ofthe gas/air mixture egressing from the burner face is accomplished by anelectric spark jumping from the insulated dished ignitor head to theburner face windings. The resulting flame releases the heat ofcombustion within the hollow space formed by the rotating water level.Radiation emenating from the flame, as well as conducted heat from theproducts of combustion, is transmitted directly to the rotating waterlevel, thus heating the water on its way through the drum. After havingbeen cooled through contact with the water level, the flue gas passesthrough the open center of the outlet stator and is sucked through theopen spaces between the transfer tubes into the blower wheel. From hereit passes through the openings cut into the conically shaped blowerwheel into the space between the outside diameter of the drum and thecylindrical housing. On its way up around the outside of the drum, the

flue gas gives off more heat to the drum surface and, finally, exitsthrough the spiral-shaped exhaust housing into the flue pipe.

To shut down the heater, power to the drive motor is shut off. Asolenoid valve e.g. in the water supply line also closes with theshut-off of power and the drum coasts to a stop. As the speed ofrotation of the drum decreases, a point is reached where the centrifugalforce is no longer adequate to maintain the water ring inside the drum,the water ring collapses and the water flows through the conical blowerwheel into the space formed by the bottom part of the housing and comesto rest. The gas supply also is shut off by e.g. a solenoid valve whichis deenergized as the power supply to the motor is shut off.

If, after a shut-down as described above, the unit is restarted, thedrive motor is energized and the rotation of the drum causes theinverted cone-shaped blower wheel to carry the water contained withinthe bottom part of the housing up into the drum. The longitudinalbaffles inside the drum make sure that the water again forms a rotatingwater ring as before. It should be noted that the cone-shaped blowerwheel serves two functions: 1. it provides for the necessary draft tosuck the combustion air into the burner, and 2. its cone shape makes itact as a pump to carry water contained in the housing at stand-stillinto the drum as soon as rotation of the drum commences. To preventwater from being sucked through the openings in the cone by the actionof the blower vanes, these openings are provided with the interiorridges 50. Therefore, only the flue gas em anating from the flame passesthrough the blower vanes while the housings water content is pumped upinto the drum upon start-up. Since a certain clearance is requiredbetween the rotating cone-shaped blower wheel and the stationaryhousing, a certain amount of water will remain in the housing but willevaporate as it is heated by the flue gas passing over it, and theresulting water vapor will pass out the exhaust together with the fluegas.

This water heater does not require the use of shaft seals of any kind toconvey water from a stationary member (the inlet stator) into therevolving drum, or to convey the water from the revolving drum intoanother stationary member (the outlet stator). The unique principle tobalance a static pressure in a stationary member by the static pressurebuilt up within a rotating water ring, as described above, lends itselfto a multitude of applications other than the present invention.Applications of this principle in the areas of liquid-cooled gas turbinerotors, speed sensing devices, seal-less pumps, or heated pumps, etc.suggest themselves.

The two circular baffles shown on the cross-sectional drawing serve notonly to space the longitudinal baffles, but also are provided with anumber of holes to force the water flowing from the inlet to the outletstator into an irregular flow pattern. The reason for this is that asthe water ring is being heated near its surface, the heated water tendsto stratify owing to the fact that warmer water becomes lighter thancolder water, i.e., its specific weight is lower with an increase intemperature. Being subjected to centrifugal force, the warmer, lighterwater would have a natural tendency to ,stay near the surface of thewater ring while the colder, heavier water would be centrifuged outtowards the inner wall of the drum. If such stratification were permitted to happen, the surface water would quickly reach the boilingpoint and turn into steam. The circular baffles are provided to preventthis Stratification from occurring. Through their irregularly spacedholes the water is forced to mix, which results in a more uniformtemperature distribution throughout the water ring. It should also benoted that there is also some heat transferred from the flue gassurrounding the drum on its outside through the drum itself, which wouldheat the water near the drums inside wall. The resulting warmer waterwould also tend to flow towards the inside owing to its reduced specificweight, thus causing some circulation in a radial direction within thewater ring. Taking these natural circulation patterns into account, itis easy to control the mixing of hot and cold water, together with ajudicial adjustment of water flow rates through the unit, to achieveoptimized performance without actually turning part of the heated waterinto steam.

I claim:

1. A liquid receptacle comprising a rotary cylindrical drum, said drumcomprising a wall, closures for the drum at each end of the wall, meansto rotate the drum, an inlet stator in the drum between the axis of thedrum and the wall thereof, an outlet stator in the drum between the axisof the drum and the same wall thereof, the stators being open at theirperipheries to provide for flow of liquid therethrough; the outletstator periphery being closer to the wall than the inlet stator, therotation of the drum causing liquid in the drum to form a ring along thedrum wall, the stators being normally submerged at their outerperipheries within the ring of liquid, the stators each comprise a pairof spaced annular flat plates located in generally transverse planesrelative to the axis of the drum.

2. The receptacle of claim 1 including radial baffles in the drumadjacent the wall thereof.

3.. The receptacle of claim 2 includingapertured circumferential bafflesin the drum intersecting the radial baffle.

4. Thereceptacle of claim 1 including vanes between the plates of boththe stators, said vanes assisting liquid flow into and out of the drum.

1. A liquid receptacle comprising a rotary cylindrical drum, said drumcomprising a wall, closures for the drum at each end of the wall, meansto rotate the drum, an inlet stator in the drum between the axis of thedrum and the wall thereof, an outlet stator in the drum between the axisof the drum and the same wall thereof, the stators being open at theirperipheries to provide for flow of liquid therethrough; the outletstator periphery being closer to the wall than the inlet stator, therotation of the drum causing liquid in the drum to form a ring along thedrum wall, the stators being normally submerged at their outerperipheries within the ring of liquid, the stators each comprise a pairof spaced annular flat plates located in generally transverse planesrelative to the axis of the drum.
 2. The receptacle of claim 1 includingradial baffles in the drum adjacent the wall thereof. 3.. The receptacleof claim 2 including apertured circumferential baffles in the drumintersecting the radial baffle.
 4. The receptacle of claim 1 includingvanes between the plates of both the stators, said vanes assistingliquid flow into and out of the drum.